End a Letter of apology

I would please like to ask your opinion on how to end a letter of apology.

Let me explain you the situation: I want to write a letter of apology addressed to the person who is responsible for my program in my University in the USA.

So, I would like to ask you how a letter of apology addressed to academic recipients (University) should end.

I try:

Hoping that you will have the generosity to accept my sincere apology (apologies?)
or
Counting with your kind generosity to accept my sincere apology (apologies?)
or
Hoping that my sincere apology (apologies?) will be kindly accepted

Yours sincerely,

.......

What do you think about it? Should I use the -ing form in my ending phrase? Any more formal / polite propositions?

rigesroz,
Your examples all sound good, although I've made one correction in red. In general, using the plural form apologies sounds more formal and respectful. If it were me, I would choose the first sentence myself because I think it has the nicest sound. Hope that helps.

Hoping that you will have the generosity to accept my sincere apologies

Each of the three suggestions (to me) sound like there is some doubt that the writer believes the reader is sufficiently generous.

I would prefer to receive "I hope that you will accept my apologies" or even "Please accept my apology".
However it is hard to create an ending not knowing what went before in the letter.

Click to expand...

I agree with all your points.

My own feeling is that it is not even necessary to refer at all to an apology being accepted or rejected. Whatever is said by way of apology earlier in the message, I would personally not re-emphasise the idea of "apology" in the conclusion, to avoid giving the impression that the recopient is being "pushed" into replying !

My "generic" suggestion in this sort of situation would be to say:

"I thank you in advance for your (kind) understanding".

In other words, all we ask is that he hears and understands, whether he accepts or not the apology is left open.